1. Technical Field
The present invention relates to a discharge lamp driving device, a light source apparatus, a projector, and a discharge lamp driving method.
2. Related Art
For example, JP-A-2012-14995 discloses a technique in which a frequency of an alternating current (AC) is changed in order to continuously maintain a stable discharge state by sustaining the state at a tip of an electrode.
As mentioned above, in a case where an alternating current is supplied to a discharge lamp, a temperature of the electrode increases in a period in which the electrode serves as an anode, and decreases in a period in which the electrode serves as a cathode. For example, in a case where a frequency of the alternating current is low, the period in which the electrode serves as an anode is lengthened, and thus a temperature of the electrode increases so that a protrusion at the tip of the electrode is easily melted.
However, for example, as disclosed in JP-A-2012-14995, in the method of simply changing a frequency, a period in which the electrode serves as a cathode is provided right after the electrode serves as an anode in the same length as the period in which the electrode serves as an anode. For this reason, in a case where a frequency of the alternating current is low, the period in which a temperature of the electrode decreases and the electrode serves as a cathode is also lengthened, and thus the temperature of the electrode cannot be sufficiently increased. Therefore, there is a case where the protrusion at the tip of the electrode may not be sufficiently melted, and thus a shape of the protrusion may not be stably maintained.